The present invention relates to reactive color inks.
There are many variables that influence the color performance (e.g., OD (optical density) and gamut volume) on media. The colorant type is an obvious factor. Brighter dyes tend to give better colors on paper. However, they are generally less lightfast. Ink and media interaction also plays a major role in the appearance of the color. If inks penetrate into the media, it is expected that the OD/gamut is low. If the ink does not spread well or the dot gain is low, the OD/gamut is generally low. Image and media gloss, in general, helps OD/gamut.
A fixer can be used to increase the durability of ink jet inks in terms of water fastness, smear and smudge fastness, by precipitating the colorant. A typical fixer contains a cationic polymer and/or an acid and/or metal salts. Cationic polymers suitable for ink jet application are polyamine (at low pH), quaternized polyamines and polyguanidine. The fixer is used to immobilize dyes and to increase durability and can be applied prior to the image is printed (underprinting) or after the image is printed (overprinting). However, the impact of the fixer on color performance is twofold. Firstly, the formation of fixer-dye complex causes hue shift in many cases. Secondly, depending on what the morphology of the fixer-dye complex is and how fast the rate of fixer-dye precipitation is, fixer-dye interaction determines where the fixer-dye complex resides on media and changes how the colors appear.
A solution to the hue shift and change in color appearance is therefore necessary.